Use new internal testutil.ErrorContains()

Signed-off-by: Daniel Nephin <dnephin@docker.com>

cli/command/network/connect_test.go

@@ -5,8 +5,8 @@ import (
 	"testing"
 
 	"github.com/docker/cli/internal/test"
+	"github.com/docker/cli/internal/test/testutil"
 	"github.com/docker/docker/api/types/network"
-	"github.com/docker/docker/pkg/testutil"
 	"github.com/pkg/errors"
 	"github.com/stretchr/testify/assert"
 	"golang.org/x/net/context"

cli/command/network/create_test.go

@@ -6,9 +6,9 @@ import (
 	"testing"
 
 	"github.com/docker/cli/internal/test"
+	"github.com/docker/cli/internal/test/testutil"
 	"github.com/docker/docker/api/types"
 	"github.com/docker/docker/api/types/network"
-	"github.com/docker/docker/pkg/testutil"
 	"github.com/pkg/errors"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"

cli/command/network/disconnect_test.go

@@ -5,7 +5,7 @@ import (
 	"testing"
 
 	"github.com/docker/cli/internal/test"
-	"github.com/docker/docker/pkg/testutil"
+	"github.com/docker/cli/internal/test/testutil"
 	"github.com/pkg/errors"
 	"golang.org/x/net/context"
 )